Fire retardant composition and cellulosic fabric treated therewith



as mammals 3,034,919 Patented May 15, 1962 3,034,919 FIRE RETARDANT COMPOSITION AND CELLU- LOSIC FABRIC TREATED THEREWITH Roger C. Steinhauer, Park Forest, Ill., assignor to Staulfer Chemical Company, New York, N.Y., a corporation of Delaware N Drawing. Filed Mar. 18, 1960, Ser. No. 15,842 16 Claims. (Cl. 117-137) This invention relates to a method of treating cellulosic fiber materials to impart thereto a substantially permanent flame resistance, and to the treating solutions therefor, as Well as the resulting flame resistant fabric.

-It is known that certain phosphorus and nitrogen containing compounds have been used to impart flame retarding properties to cellulosic fibers or fabrics by impregnating such fabrics with solutions of such compounds then drying the fabrics.

One of the more effective of the prior art treatments involves the impregnation of cellulosic fabrics with a solution of an aziridinyl phosphine oxide followed by the heat polymerization of such compound to form a flame retarding polymer coating on the fibers of the fabric. One of the disadvantages of this procedure is in the danger and difliculty involved in controlling the stability of the treating bath and the rate of polymerization of the compound on the fibers. The polymerization step is sometimes dangerously 'violent, particularly where large add-ons are required for high degrees of flame resistance.

'1 have now found that these disadvantages can be overcome by the use of a treating bath containing a combination of an aziridinyl phosphine oxide and another phosphorus and nitrogen containing composition selected from the group consisting of an ammonium hydroxide modified reaction product of anhydrous ammonia and phosphorus pentoxide, a condensation reaction product of ethylenediamine and a reaction product of anhydrous ammonia and phosphorus pentoxide, and the condensation reaction products of ethylenediamine and a reaction product of anhydrous ammonia and phosphorus oxychloride.

By the use of such combinations of treating agents in a single treating bath I am able to impart a superior flame resistant effect to the treated fabric.

As Will be pointed out below the use of my new combination of treating agents in a single fabric treating bath results in a synergistic improvement in the flame resistance of the treated fabric.

The treating solutions of this invention may be used to improve the flame resistance of cellulosic materials such as cotton, ramie, jute, paper, wood, wood pulp, rayon and various textile materials of cellulosic origin.

Another advantage in the use of my new procedure is that it permits the use of much smaller amounts of the quite expensive aziridinyl phosphine oxide component to obtain equivalent or superior flame resistant effects in the treated fabrics.

In accordance with my invention the two types of treating agents are dissolved, or in some cases suspended, in an aqueous bath and the fabric to be flame-proofed is dipped into, or impregnated with such solution, then dried and cured at about 150 C. for a sufficient period to effect a co-action and polymerization of the flameproofing agents to form an in situ deposition or attachment of the flameproofing polymer composition in the fabric.

For optimum flameproofing effect the two components should be used in substantially equal proportions by weights. However, satisfactory flameproofing results may be obtained with proportions of 1 to 3 parts of either component to 1 part of the other component. However, in all cases it has been found that a satisfactory degree of permanent flame resistance is not obtained unless the total amount of the flameproofing composition deposited on or attached to the fabric is at least 10% by weight of the fabric, and preferably in the order of 11 to 15% by weight of the fabric. These amounts of the flameproofing composition refer to amounts of add-on retained by the fabric after the treated and cured fabric is further treated with a solution of a softening agent and rinsed with water.

The aziridinyl compounds which are suitable for use in the preparation of the new flameproofing compositions include the his and tris aziridinyl phosphine oxides and sulfides, but preferably the tris (l-aziridinyl) phosphine oxide (hereinafter sometimes designated at APO) having the formula OE: 0112 a The anhydrous ammonia-phosphorus pentoxide reaction product, which may be used as the starting material for the ammonium hydroxide modified reaction product used in the present invention, is a well-known commercial product of indefinite structure and may be produced by any one of several known methods. It may be suitably made by burning elemental phosphorus with dry air to form P 0 substantially in vapor form and immediately reacting such P 0 with gaseous NH in excess over the amount which Will react with the P 0 and separating the reaction product in the form of a water soluble finely divided white product. The product analysis shows 70- P 0 510% nuclear or amide nitrogen, and 12-18% free or ammoniacal nitrogen. It is probably a mixture of several different compounds having different structural formulas and degrees of polymerization. This product is then further modified by dissolving it in an excess of a concentrated ammonium hydroxide solution and subsequently separating the excess ammonium hydroxide from the viscous liquid product. If desired the liquid product may be recovered in solid form by vacuum drying, but generally is employed in its liquid form. The procedure is described in US. Patent 2,964,377. Again, the composition can not be defined by structure, but represents a mixture largely in polymeric form with a higher ratio of amide nitrogen to total phosphorus than the starting anhydrous ammonia P 0 reaction product. Such product is hereinafter sometimes designated as VFP-56.

Further suitable phosphorus and nitrogen containing compounds which may be used in combination with the aziridinyl compounds are described in, and may be produced in accordance with the procedure of US. patent application Serial Number 768,041 filed October 20, 1958. The products described therein are condensation reaction products of ethylenediamine with the reaction products of anhydrous ammonia and P 0 or F001;, and contain at least one amide nitrogen bonded directly to at least one phosphorus atom. In general, the products are satisfactory for use in the present invention where the amount of ethylenediamine employed is suflicient to condense with from one-third to all of the amide nitrogen atoms present in the starting anhydrous NH P O or NH P001 reaction product. Generally the product resulting from the reaction of the NH P O reaction product with about one-third of the theoretical reacting proportion of ethylenediamine is the preferred product, and is hereinafter sometimes designated as VSF-lOO. The use of up to theoretical proportions of the ethylenediamine gives suitable products for use in the present invention but does not have suflicient advantage over the preferred product to warrant the use of the greater amounts of ethylenediamine.

In the preparation of a suitable flameproofing solution or bath of present invention the aziridinyl compound and the modified NH -P O compound are dissolved, in the desired proportions, in water as a common solvent in suitable concentration, generally about to 35% total concentration of the active agents. If desired, softening agents may be introduced into the bath, but generally it is preferred to postpone the softening treatment until after the fibrous material has been impregnated and cured. In this manner the softening treatment serves to remove the excess soluble fiameproofing components and results in a softer or more desirable hand to the fabric.

In the flameproofing procedure the cellulosic fibers or fabric is saturated with the flameproofing solution, the excess solution drained out, or squeezed out by pressure rollers, etc., and the treated cellulosic material dried at about 100 C., and then heated from 2 to 10 minutes at a curing temperature of about 140 to 160 C. The treated cured cellulosic fabric is then soaked for about minutes at 110115 C. in an aqueous solution containing about 0.5 to 2.0% of a softening agent such as sulfonated castor oil, soluble resins or any of a number of commercial anionic or cationic textile softening agents; the excess solution removed and the fabric rinsed with water then dried at about 100 C. By weighing the fabric before and after the above treatment the amount of add-on of the flameproofing composition may be determined. The amount of the treating composition retained by the fabric after a number of laundering cycles determines the degree of permanency of the flame resistant effect. However, this effect is more realistically determined by actual flame resistance measurements.

The degree of flame resistance is determined by the vertical Bunsen flame test as described in Federal Specification CCC-T-191-b Method 5902. Briefly, the test consists in applying a gas flame for a period of 12 seconds under the center of the bottom edge of a 2.75 wide 12" long strip of the test fabric held in a vertical position. The time required for the flame to extinguish itself, including the 12 second period, and the length of the charred portion are determined. Generally, a burning time of less than 12 seconds and a char length of less than 5-6 inches are considered as representing a very satisfactory degree of flame resistance.

The degree of permanency of the flameproofing treatment may be determined by the number of laundering cycles which are possible before the fabric loses its flame resistance as measured against a standard degree of flame resistance. However, for the purposes of the present invention the degree of permanency is rated by the degree of flame resistance retained after an accelerated washing procedure consisting in subjecting the test fabric for one hour to the action of a boiling solution of 500 cc. water containing 0.3% laundry soap and 0.2% soda ash, then rinsing the fabric with distilled water and drying at 100 C. Such washing treatment is equivalent to about 15 normal laundering cycles.

In the preparation of a typical flameproofing bath an anhydrous ammonia-P 0 reaction product (i.e. produced by burning elemental phosphorus with dry air to form P 0 vapors, and immediately reacting such P 0 with an excess of gaseous NH;,, and separating the reaction product in the form of a finely divided white granular material) having an analysis of 73.55% P 0 6.58% nuclear or amide nitrogen and 13.22% of ammonium nitrogen was stirred into a large volume of an ammonium hydroxide (28% NH solution and allowed to stand overnight at room temperature The excess ammonium hydroxide was decanted off leaving a lower viscous layer of the modified NH -P O reaction product, having an analysis of 52.8% P 0 6.3% amide nitrogen and 12% ammonium nitrogen. Equal parts by weight of this modified reaction product and tris (l-aziridinyl) phosphine oxide were dissolved in water to give a solution of about concentration of the combined flameproofing agents.

all

The concentration of the treating bath may be varied when treating the fabric to be flameproofed as a means of partially controlling the amount of add-on in the fabric.

For example, a bath of the above composition in a 15% concentration was used to impregnate a piece of 9 oz. cotton twill fabric. After draining off the excess solution and drying the treated fabric at a temperature of C. for 30 minutes the fabric had an add-on of 16.0% (by weight) of the treating composition. After curing at 150 C. for 5 minutes and subsequently soaking the cured fabric for 15' minutes at 115 C. in a 0.5% aqueous solution of a commercial soluble resin textile softener (Atco-Rezsoft) rinsing for 10 minutes in distilled water and drying the fabric at about 100 C. it was found that the fabric retained an add-on of 11.4% of the flameproofing composition. The fabric was flame resistant and had a hand substantially equivalent to that of the original untreated fabric. The fabric was then boiled for 1 hour in water containing 0.2% soda ash and 0.3% laundry soap, rinsed in distilled water and dried. After this washing treatment the fabric still retained an add-on of 11.3%. When tested for flame resistance by the vertical Bunsen test the flame time was 10.5 seconds and the char length was 6.3 inches. These results show that the flameproofing elfect was substantially permanent against the effect of repeated laundering cycles.

In another example using a 30% concentration of the above flameproofing bath the add-on after the softening treatment was found to be 13.7%. After boiling for one hour in the soap-soda ash solution the fabric showed a flame time of 8 seconds and a char length of 5.0 inches, with no afterflame when the test flame was removed.

A piece of this treated fabric after the softening treatment was subjected to 15 laundering cycles in accordance with the procedure of Method 5556, Federal Specification CCCT191b and tested for flame resistance in accordance with Method 5902. The results showed no after-flame (after removal of Bunsen flame) and only 4.2 inches of char length after the 15th laundering cycle. These tests show the superior flameproofing effect obtained by the combined use of tris (l-aziridinyl) phosphine oxide (known as APO) and an ammonium hydroxide modified NH P O reaction product (known as VFP- 56). Further, these tests show that 15' standard laundering cycles are not quite as drastic as the one hour soap and soda ash boil test used in this specification to evaluate the permanency of the flame resistance effect. A substantial degree of permanent flame resistance is indicated where the test fabric fails to burn its entire length after the flame is removed. Thus, char lengths of less than 10 inches indicate flame resistance. Char lengths of less than 6 inches are considered as indicating a highly satisfactory degree of permanent flame resistance.

In a further example a treating bath was made by dissolving in water equal parts by weight of APO (tris aziridinyl phosphine oxide) and the condensation product of ethylenediamine with the reaction product of anhydrous NH and P 0 described above, where the molecular proportion of ethylenediamine was equivalent to one-third of the amino nitrogen present in the anhydrous NH P O reaction product. (For sake of brevity this condensation product is designated as VSF-lOO, its trade name.) Suitable concentrations of the combination of agents may be within the range of 10 to 30%.

In a typical example a treating bath containing 7.5% APO and 7.5% VSF-100 was used to impregnate a piece of 9 02. cotton twill fabric. After draining off the excess of the treating solution from the fabric, the fabric was dried at a temperature of approximately 100 C. for 30 minutes. The fabric having an initial add-on of 17.3% was cured at C. for 10 minutes, then given a softening treatment by soaking for 15 minutes at 1l0-115 C. in a 0.5% aqueous solution of a commercial solubleresin textile softener (Atco-Rezsoft) and rinsing for 10 6 minutes in a stream of distilled water to remove residual Table II water solubles. After drying the fabric at 100 C. it was found to have retained an add-on of 11.9% of the com- Treating bath Add. bined treating agents. To test the permanency of the E g 2 flame resistance the test piece was boiled for one hour 5 Percent inf" 561555.13 fli fies' in a water solution of 0.2% soda ash and 0.3% laundry 001m cmpnents Ram percent soap. After rinsing in distilled water and drying, the test fabric retained an add-on of 10.3%. When tested by the vertical Bunsen test for flame resistance of the flame aYZ V EI oi 20+ time was found to be 9 seconds and a char length of 5.7 Y 6 78 1M 14 m inches. This example shows a highly satisfactory degree 15.1 mj 'xggbw 1.00 11.4 10 6.3 of permanent flame resistance.

The following table shows the results of a number of i i 56+ 9 test examples using the above test conditions except for 6 11 the variations in bath concentrations and the amounts of 5 6---" 2 .9 20.3% V 1" 68 3-3 9.5 add-on retained by the test fabric after the softening treat- 12 2 gi;2 65 9 61 3 0 0 ment. Also included in the table are results obtained, for 7.6 APO. comparative purposes, when using the treating agents sin- 7;X %i m0 gly under comparative treating and add-on conditions. Zi -6 Table I 10---- 19.8 m gg s i 100+ 1.61 14.9 9.0 5.3

Percent i i1 i i1i,iii'0 The results in Tables I and II indicate that at equiva- EL Treating agent Bath 55;; ggg gggg lent bath concentrations the add-on and char length decone. Init. s0 ftenterminations show that optimum permanent flame re- 655 Flame Char sistance is obtained with ratios of VFP-56 or VSF-lOO Eleni; Time length to APO of about one. However, highly satisfactory (secs') (IHS') permanent flame resistance may be obtained when using 15 11 2 2 E a wide range of proportions of the treating agents at 25 1 different treating bath concentrations. It has been found 15 17.3 9.8 20+ B.E. that ratios within the range of 3:1 and 1:3 of the modified f8 &3 13$ NH P O products to the APO with treating bath con- G APO 53% 18.9 g; centrationsof 15- 30% are satisfactory for the treatment gg'fgfig? 10 5 3 of cellulose fabncs to obtain a sansfactory degree of I vi s 7' i+ 1s 13 4 11 1 1o 0 6 1 permanent flame reslstance' APO Treating baths of lower concentration may be used by J V1; 6 25 double dipping or double impregnation of the fabric in Km" i g ig 10 M 7,8 order to secure at least a rmmmum effective add-on after L i k tf 15 16,7 In 9.7 5.7 s1(;ftte m1n5g%treatment of about 10% and preferably about i; 25 1&2 Higher effective add-on may be desirable with some fabrics depending on the weight and texture of the cloth NOTE B E'=BumS eumelengm to be treated. Lighter weight fabrics generally burn more readlly and require a somewhat higher add-on for The results of the examples in the above table show two things, namely, that an add-on of the treating agents after softening of at least 10% is needed to impart permanent flame resistance to the fabric, and that a definite synergistic elfect on flame resistance results from the combination use of APO with either the VFP-56 or VSF-lOO type derivatives of an NH -P O reaction product. For example, using a treating bath containing 12.5% VFP-S 6 and 12.5% APO the resulting treated fabric had a flame time of 9. 0 seconds and a char length of 4.7 inches. When using a 25% concentration of either agent alone the best results gave a flame time of 9.7 seconds and a char length of only 5 .7 inches. In like manner when using the VSF- 100 and APO combination the 4.4 inch char length is superior to either the 6.1 or 5.7 inch char lengths obtained with the separate components alone.

Using treating baths of only 15% concentration the synergistic effect is more marked, though the char lengths are higher due to the lower percentage of add-on of the treating agents.

In another series of examples it was demonstrated that variations in the proportions of the treating agents in the bath are not highly critical within the range of about 1 to 3 parts of the VFP-S 6 or VSF-100 component to one part of APO when using equivalent bath concentrations.

Table II shows a number of examples using several different ratios of VFP-56 or VSF-lOO to APO at several treating bath concentrations. The fabric treating, curing and testing conditions were substantially the same as those employed in the other examples described above.

effective flame resistance.

In a typical example a 5 ounce cotton poplin cloth was dipped into an aqueous bath containing 70 parts of VFP-56 and 70 parts of APO in 260 parts of water (by weight), wrung out and dried for 10 minutes at C. and then redipped, again wrung out and dried, then cured for 15 minutes at 150 C. The treated cloth was further treated in a 0.5% aqueous solution of a soluble resin textile softening agent (Atco Rezsoft) for 15 minutes at C. The resulting cloth after rinsing in water and drying had an add-on of 19.4% of the active ingredients. After washing the cloth for one hour in a boiling solution of 0.3% laundry soap and 0.2% soda ash, rinsing and drying, the effective add-on of the treating agents was 15.2%. On testing the washed cloth for flame resistance by the vertical Bunsen method it was found to have a flame time of 7 seconds and a char length of 4.9 inches.

A piece of 8.5 ounce cotton sateen cloth under equivalent treating conditions had an effective add-on of 13.3% a flame time of 9.7 seconds and a char length of 4.0 inches.

The use of the tris aziridinyl phosphine oxide has been illustrated in the above examples but the bis aziridinyl phosphine oxide which contains two instead of three of the active aziridinyl groups is only slightly less effective for forming flame resistant copolymer coatings on cellulosic fabrics.

The following example shows a typical application where an ethylenediamine condensation product with a reaction product of anhydrous ammonia and phosphoryl chloride (POCl is employed in combination with an equal proportion by weight of tris aziridinyl phosphine oxide.

Phosphorus oxychloride was reacted in known manner with six moles of anhydrous ammonia (NI-1 to form phosphoric triamide (PO(NH which was separated and recovered as a granular or powdered product.

28.5 parts by weight of this phosphoric triamide was mixed with 18.0 parts of ethylenediamine forming a gummy mass which was then heated for about three hours. On cooling to room temperature the reaction product was a soft, white hygroscopic solid having an analysis of 52.2% P 32.3% total nitrogen, with 2.5% ammonium nitrogen. This product and the method of producing it are as described in US. patent application Ser. No. 768,041, filed October 20, 1958.

Equal parts by weight of this reaction product and tris (l-aziridinyl) phosphine oxide were dissolved in water to a concentration of 26.2% active ingredients. This solution was used to impregnate a piece of 9 oz. cotton twill cloth. The treated cloth was then dried for about 10 minutes at 100 C. and then cured for minutes at 150 C., then treated in a 0.5% solution of a soluble resin textile softening agent (Atco Rezsoft) for 15 minutes at 110 C., then rinsed in water and dried at 100 C. The thus treated cloth had an add-on of 15.7% of the active agents. After laundering this test piece of cloth by boiling for one hour in a 0.3% soap and 0.2% soda ash solution the add-on was 12.8%. After this severe washing treatment the cloth was tested for flame resistance by the vertical Bunsen method and found to have a flame time of 10.0 seconds and a char length of only 5.4 inches.

The above examples and descriptive matter are intended to be illustrative of the invention and no limitations therefrom are implied except as defined in the appended claims.

I claim:

1. A treating solution for the impregnation of cellulosic fibers and fabrics to impart flame resistance thereto, which comprises an aqueous solution of 1035% concentration of a mixture of one part of an aziridinyl phosphine oxide and one-third to three parts by weight of a phosphorus and nitrogen containing composition selected from the group consisting of (a) an ammonium hydroxide modified reaction product of anhydrous ammonia and phosphorus pentoxide, (b) a condensation reaction product of ethylenediamine with a reaction product of anhydrous ammonia and phosphorus pentoxide, and (c) a condensation reaction product of ethylenediamine with a reaction product of anhydrous ammonia and phosphorus oxychloride.

2. A product comprising cellulosic fabric and the product of claim 1 in an amount sufficient to act as a fire retardant therefor.

3. A treating solution in accordance with claim 1 where the aziridinyl phosphine oxide is tris (l-aziridinyl) phosphine oxide.

4. A product comprising cellulosic fabric and the product of claim 3 in an amount sufficient to act as a fire retardant therefor.

5. A treating solution in accordance with claim 1 where the aziridinyl phosphine oxide and the phosphorus and nitrogen containing composition are used in substantially equal proportions by weight.

6. A product comprising cellulosic fabric and the product of claim 5 in an amount suflicient to act as a fire retardant therefor.

7. An aqueous solution of 10-35% concentration of a mixture of substantially equal parts by weight of tris (l-aziridinyl) phosphine oxide and an ammonium hydroxide modified reaction product of anhydrous ammonia and phosphorus pentoxide.

8. A product comprising cellulosic fabric and the product of claim 7 in an amount sufficient to act as a fire retardant therefor.

9. An aqueous solution of 1035% concentration of a mixture of substantially equal parts by weight of tris (l-aziridinyl) phosphine oxide and a condensation reaction product of ethylenediamine with a reaction product of anhydrous ammonia and phosphorus pentoxide.

10. A product comprising cellulosic fabric and the product of claim 9 in an amount sufficient to act as a fire retardant therefor.

11. An aqueous solution in accordance with claim 9 where the condensation reaction product of ethylenediamine with the reaction product of anhydrous ammonia and phosphorus pentoxide results from the use of an amount of ethylenediamine equivalent to about one-third of the amount capable of reacting with the reaction product of anhydrous ammonia and phosphorus pentoxide.

12. A product comprising cellulosic fabric and the product of claim 11 in an amount sufiicient to act as a fire retardant therefor.

13. An aqueous solution of 10-35% concentration of a mixture of substantially equal parts by weight of tris (l-aziridinyl) phosphine oxide and a condensation reaction product of ethylenediamine with a reaction product of anhydrous ammonia and phosphorus oxychloride.

14. A product comprising cellulosic fabric and the product of claim 13 in an amount sufficient to act as a fire retardant therefor.

15. An aqueous solution in accordance with claim 13 where the condensation reaction product of ethylenediamine with the reaction product of anhydrous ammonia and phosphorus oxychloride results from the use of an amount of ethylenediamine equivalent to about onethird of the amount capable of reacting with the reaction product of anhydrous ammonia and phosphorus oxychloride.

16. A product comprising cellulosic fabric and the product of claim 15 in an amount suflicient to act as a fire retardant therefor.

References Cited in the file of this patent UNITED STATES PATENTS 2,901,444 Chance et al. Aug. 25, 1949 

1. A TREATING SOLUTION FOR THE IMPREGNATION OF CELLULOSIC FIBERS AND FABRICS TO IMPART FLAME RESISTANCE THERETO, WHICH COMPRISES AN AQUEOUS SOLUTION OF 10-35% CONCENTRATION OF A MIXTURE OF ONE PART OF AZIRIDINYL PHOSPHINE OXIDE AND ONE-THIRD TO THREE PARTS BY WEIGHT OF A PHOSPHORUS AND NITROGEN CONTAINING COMPOSITION SELECTED FROM THE GROUP CONSISTING OF (A) AN AMMONIUM HYDROXIDE MODIFIED REACTION PRODUCT OF ANHYDROUS AMMONIA AND PHOSPHORUS PENTOXIDE, (B) A CONDENSATION REACTION PRODUCT OF ETHYLENEDIAMINE WITH A REACTION PRODUCT OF ANHYDROUS AMMONIA AND PHOSPHORUS PENTROXIDE, AND (C) A CONDENSATION REACTION PRODUCT OF ETHYLENEDIAMINE WITH A REACTION PRODUCT OF ANHYDROUS AMMONIA AND PHOSPHORUS OXYCHLORIDE.
 9. AN AQUEOUS SOLUTION OF 10-35% CONCENTRATION OF A MIXTURE OF SUBSTANTIALLY EQUAL PARTS BY WEIGHT OF TRIS (1-AZIRIDINYL) PHOSPHINE OXIDE AND A CONDENSATION REACTION PRODUCT OF ETHYLENEDIAMINE WITH A REACTION PRODUCT OF ANHYDROUS AMMONIA AND PHOSPHORUS PENTOXIDE. 